Rating Radio Group Example

Read This First

The code in this example is not intended for production environments. Before using it for any purpose, read this to understand why.

This is an illustrative example of one way of using ARIA that conforms with the ARIA specification.

There may be support gaps in some browser and assistive technology combinations, especially for mobile/touch devices. Testing code based on this example with assistive technologies is essential before considering use in production systems.
The ARIA and Assistive Technologies Project is developing measurements of assistive technology support for APG examples.
Robust accessibility can be further optimized by choosing implementation patterns that maximize use of semantic HTML and heeding the warning that No ARIA is better than Bad ARIA.

About This Example

Following is an example of a rating input that demonstrates the Radio Group Pattern. The rating is indicated by the number of stars selected by the user.

Similar examples include:

Rating Slider Example: Horizontal slider that demonstrates using aria-valuetext to make it easy for assistive technology users to understand the meaning of the current value chosen on a ten-point satisfaction scale.
Radio Group Example Using aria-activedescendant: Radio button group that uses aria-activedescendant for managing keyboard focus.
Radio Group Example Using Roving tabindex: A radio button group that uses roving tabindex for managing keyboard focus.

Example

Rating

Accessibility Features

To enhance perceivability when operating the radios, visual keyboard focus and hover are styled using CSS:
- The focus ring has a width of 2 pixels and at least 2 pixels of spacing between it and the star borders.
- The cursor changes to a pointer when hovering over the stars so it is easier to perceive that the rating stars are interactive.
To ensure the borders of the stars and the focus ring have sufficient contrast with the background when high contrast settings invert colors, the color of the borders are synchronized with the color of the text content. For example, the color of the focus ring border is set to match the foreground color of high contrast mode text by specifying the CSS currentcolor value for the stroke property of the inline SVG polygon to draw the star borders and rect element used to draw the focus ring border. To make the background of the polygon and rect elements match the high contrast background color, the fill-opacity attribute of the rect is set to zero. If specific colors were instead used to specify the stroke and fill properties, those colors would remain the same in high contrast mode, which could lead to insufficient contrast between the star and the background or even make them invisible if their color matched the high contrast mode background.
Note: The SVG element needs to have the CSS forced-color-adjust property set to auto for the currentcolor value to be updated in high contrast mode. Some browsers do not use auto for the default value.

Keyboard Support

Key	Function
`Tab`	Moves focus to the checked `radio` button in the `radiogroup`. If a `radio` button is not checked, focus moves to the first `radio` button in the group.
`Space`	If the `radio` button with focus is not checked, changes the state to `checked`. Otherwise, does nothing. Note: The state where a radio is not checked only occurs on page load.
`Down arrow` `Right arrow`	Moves focus to and checks the next `radio` button in the group. If focus is on the last `radio` button, moves focus to the first `radio` button. The state of the previously checked radio button is changed to unchecked.
`Up arrow` `Left arrow`	Moves focus to and checks the previous `radio` button in the group. If focus is on the first `radio` button, moves focus to and checks the last `radio` button. The state of the previously checked radio button is changed to unchecked.

Role, Property, State, and Tabindex Attributes

Role	Attributes	Element	Usage
`none`		`svg`	The use of the `none` role on the SVG element ensures assistive technologies do not interpret the SVG element as an image or some other role.
`radiogroup`		`div`	Identifies the `div` element as a container for a group of `radio` buttons. Is not focusable because focus is managed using a roving tabindex strategy as described below.
	`aria-labelledby="ID_REFERENCE"`	`div`	Refers to the element that contains the label of the radio group.
`radio`		`g`	Identifies the `g` element as an ARIA `radio` button.
	`aria-label="name"`	`g`	Defines an accessible name that identifies the number of stars associated with the radio button (e.g. "one star", two stars", ..).
	`tabindex="-1"`	`g`	Makes the element focusable but not part of the page `Tab` sequence. Applied to all radio buttons contained in the radio group except for one that is included in the page `Tab` sequence. This approach to managing focus is described in the practice for Managing Focus Within Components Using a Roving tabindex.
	`tabindex="0"`	`g`	Makes the radio button focusable and includes it in the page `Tab` sequence. Set on only one radio in the radio group. On page load, is set on the first radio button in the radio group. Moves with focus inside the radio group so the most recently focused radio button is included in the page `Tab` sequence. This approach to managing focus is described in the practice for Managing Focus Within Components Using a Roving tabindex.
	`aria-checked="false"`	`g`	Identifies `radio` buttons which are not checked. CSS attribute selectors (e.g. `[aria-checked="false"]`) are used to synchronize the visual states with the value of the `aria-checked` attribute. The CSS `::before` pseudo-element is used to indicate visual state of unchecked radio buttons to support high contrast settings in operating systems and browsers.
	`aria-checked="true"`	`g`	Identifies the `radio` button which is checked. CSS attribute selectors (e.g. `[aria-checked="true"]`) are used to synchronize the visual states with the value of the `aria-checked` attribute. The CSS `::before` pseudo-element is used to indicate visual state of checked radio buttons to support high contrast settings in operating systems and browsers.

JavaScript and CSS Source Code

CSS: radio-rating.css
Javascript: radio-rating.js